The present disclosure relates to aircraft environmental control systems. More specifically, the present disclosure relates to a fan and compressor housing for an air cycle machine.
Air cycle machines are used in environmental control systems in aircraft to condition air for delivery to an aircraft cabin. Conditioned air is air at a temperature, pressure, and humidity desirable for aircraft passenger comfort and safety. At or near ground level, the ambient air temperature and/or humidity is often sufficiently high that the air must be cooled as part of the conditioning process before being delivered to the aircraft cabin. At flight altitude, ambient air is often far cooler than desired, but at such a low pressure that it must be compressed to an acceptable pressure as part of the conditioning process. Compressing ambient air at flight altitude heats the resulting pressured air sufficiently that it must be cooled, even if the ambient air temperature is very low. Thus, under most conditions, heat must be removed from air by the air cycle machine before the air is delivered to the aircraft cabin.
Air cycle machines typically include rotating components mounted to a tie rod and a static housing surrounding the rotating components. The static housing can include multiple pieces that are fastened together. The static housing pieces typically include soft material seals positioned between the static housing and the rotating components. For instance, the soft material seals can be a polyimide material. The soft material seals allow the rotating components to easily rotate within the static housing and provide a surface upon which the rotating components can slide. The soft material seals are also designed to control air leakage between the parts they are sealing. Some air leakage can be allowed so that the air can be used to lubricate and cool journal bearings in the air cycle machine.